Electrical power generation devices using hydrocarbons such as natural gas, gasoline, diesel, military logistic fuels, and other similar materials as the energy storage medium have several advantages over batteries. Such advantages include, for example, higher energy density, easier transportation, operation with a variety of supply infrastructures, short recharge periods, and other benefits.
Some devices, including fuel cells, operate using syngas, a mixture of H2 and CO. Syngas having H2 and CO can be produced from hydrocarbons by using catalysts in fuel reformers. Using the catalysts permits a rapid reaction rate for fuel-rich reaction that has lower reaction temperature. For example, the catalysts lower the effective activation energy so that products are able to reach their chemical equilibrium state at reduced temperatures resulting in near-theoretical yields (maximum amounts attainable) of H2 and CO in the syngas. However, sulfur compounds and/or higher hydrocarbons present in the energy storage medium can easily poison or deposit carbon (coking) on the catalyst, which degrades performance and shortens the useful life of the catalyst for reformer operations. Catalysts also suffer from other deactivation mechanisms such as sintering.
To address such drawbacks, expensive noble-metal-based catalysts, such as rhodium, have been used. In addition, sub-systems, for example, for pre-desulfurization and/or water management, and complicated control systems have been used. Such remedies are not well-suited for portable and/or small power scale applications where the system size, weight, and parasitic power consumption are important. In addition, such remedies are expensive.
In addition to using catalyst, syngas having H2 and CO can also be generated in fuel-rich reaction at elevated temperature, for example, using pure oxygen instead of air as oxidizer to reduce the need for thermal diluents or using an external energy source (for example, plasma) to provide excess energy in the reactants and thus accelerate the reaction rate. However, such systems are very large, very complex, and very expensive.
A known combustor operates with a combustion zone configured for receiving fuel-lean energy storage media from a first spiraling path in a spiral heat exchanger to produce combustion products. The combustion products include H2O and CO2, which are expelled through a second spiraling path and preheat the incoming reactants in the first spiraling path. The known combustor is able to create a higher temperature reaction zone using air as oxidizer without external energy input, but the combustion products are not capable of being used in systems and processes requiring a syngas with a higher concentration of H2 and CO than the resulting effluent from combustion.
Fuel reforming processes and systems that produce one or more improvements would be desirable in the art.